Semiconductor relay device

ABSTRACT

A semiconductor relay device includes: an oscillator unit configured to output an oscillation signal based on an input signal; a first inductor and a second inductor that are magnetically coupled to each other; a driving unit configured to drive the first inductor based on the oscillation signal output from the oscillator unit; a rectifier unit configured to rectify a signal output by the second inductor; and a connecting unit configured to electrically connect or disconnect a first terminal and a second terminal to or from each other based on a signal rectified by the rectifier unit.

TECHNICAL FIELD

The present invention relates to a semiconductor relay device.

BACKGROUND ART

There is known a semiconductor relay device including: an oscillatorcircuit that oscillates depending on an input signal; an inductor unitthat converts a transmission signal from the oscillator circuit into anelectromagnetic signal; a rectifier circuit that rectifies an outputsignal from the inductor unit; a charging and discharging circuit thatcharges and discharges a signal rectified by the rectifier circuit; andan output MOSFET of which switching is performed depending on potentialdifference generated between the ends of the charging and dischargingcircuit (Patent Literature 1).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open Publication No.2007-124518

SUMMARY Technical Problem

In the semiconductor relay device according to Patent Literature 1, thetransmission signal from the oscillator circuit directly flows throughthe inductor unit which is a load of the oscillator circuit, and isconverted into the electromagnetic signal. Thus, there is a possibilitythat the inductor unit cannot be supplied with sufficient current andswitching of the output MOSFET cannot be appropriately performed.

Solution to Problem

According to a first aspect of the present invention, a semiconductorrelay device includes: an oscillator unit configured to output anoscillation signal based on an input signal; a first inductor and asecond inductor that are magnetically coupled to each other; a drivingunit configured to drive the first inductor based on the oscillationsignal output from the oscillator unit; a rectifier unit configured torectify a signal output by the second inductor; and a connecting unitconfigured to electrically connect or disconnect a first terminal and asecond terminal to or from each other based on a signal rectified by therectifier unit.

Advantageous Effects of Invention

According to the present invention, switching can be appropriatelyperformed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of asemiconductor relay device according to an embodiment.

FIG. 2 is a diagram illustrating an example of a circuit configurationof the semiconductor relay device according to the embodiment.

FIG. 3 is a timing chart illustrating an operation example of thesemiconductor relay device according to the embodiment.

FIG. 4 is a diagram illustrating an example of a configuration of asemiconductor relay device according to a first variation.

FIG. 5 is a diagram illustrating another configuration example of thesemiconductor relay device according to the first variation.

FIG. 6 is a diagram illustrating a configuration example of asemiconductor relay device according to a second variation.

FIG. 7 is a diagram illustrating an example of a configuration of asemiconductor relay device according to a third variation.

FIG. 8 is a diagram illustrating another configuration example of thesemiconductor relay device according to the third variation.

FIG. 9 is a diagram illustrating a configuration example of asemiconductor relay device according to a fourth variation.

DESCRIPTION OF EMBODIMENTS Embodiment

FIG. 1 is a diagram illustrating a configuration example of asemiconductor relay device according to an embodiment. A semiconductorrelay device 1 is a semiconductor relay having a first terminal 11, asecond terminal 12, a third terminal 13, and a fourth terminal 14. Thesemiconductor relay device 1 includes an oscillator unit 20, a drivingunit 30, an inductor unit 40, a rectifier unit 50, a smoothing/chargingand discharging unit 60, and a connecting unit 90. The semiconductorrelay device 1 switches between electrical connection and disconnectionbetween the third terminal 13 and the fourth terminal 14 depending on asignal input to the first terminal 11 and the second terminal 12.

The first terminal 11 and the second terminal 12 constitute an inputunit to which an electrical signal can be input from outside of thesemiconductor relay device 1. In the semiconductor relay device 1, eachunit (oscillator unit 20, driving unit 30, or the like) of thesemiconductor relay device 1 operates depending on a signal Vin suppliedthrough the first terminal 11 and the second terminal 12.

The third terminal 13 and the fourth terminal 14 constitute an outputunit from which an electrical signal can be output to outside of thesemiconductor relay device 1. In the semiconductor relay device 1,switching is performed depending on a signal Vin, and an electricalsignal depending on the signal Vin is transferred (transmitted) tooutside through the third terminal 13 and the fourth terminal 14.

The oscillator unit 20 is constituted by an oscillator circuit (OSC) andgenerates a signal (hereinafter, referred to as an oscillation signalCLK) with a predetermined frequency and period on the basis of thesignal Vin input through the first terminal 11. When the signal level ofthe signal Vin supplied from the first terminal 11 changes from lowlevel (for example, ground voltage or reference voltage) to high level(for example, power-supply voltage), the oscillator unit 20 generates anoscillation signal CLK and starts outputting the oscillation signal CLK.It can also be said that the oscillator unit 20 oscillates when thesignal Vin is in an enabled state (at high level). The oscillator unit20 outputs the generated oscillation signal CLK to the driving unit 30.

The inductor unit 40 has a plurality of inductors (coils) that aremagnetically coupled to each other and functions as a transformer thattransmits energy. The inductor unit (transformer) is also avoltage-converter unit 40 that transforms voltage. Note that the methodof transmitting energy from a primary side to a secondary side may be aflyback mode or a forward mode. That is, the inductor unit 40 may be aflyback transformer or a forward transformer. Furthermore, the inductorunit 40 may have a core (for example, iron core).

The driving unit 30 drives the inductor unit 40 on the basis of theoscillation signal CLK output by the oscillator unit 20. When the signallevel of the signal Vin becomes high level and the oscillation signalCLK is input from the oscillator unit 20, the driving unit 30 startssupplying electric power from the first terminal 11 to primary-sideinductors of the inductor unit 40. The driving unit 30 is an amplifierunit 30 and increases (amplifies) current and voltage to be supplied tothe inductor unit 40 compared to a case where the oscillation signal CLKfrom the oscillator unit 20 is directly input to the inductor unit 40.

The rectifier unit 50 has a rectifier element and functions to convertalternate current (AC) to direct current (DC). The rectifier unit 50 iselectrically connected to secondary-side inductors of the inductor unit40, and rectifies AC voltage induced in the secondary-side inductors ofthe inductor unit 40 to DC voltage. The rectifier unit 50 outputs asignal V1 obtained by the rectification to the smoothing/charging anddischarging unit 60.

The smoothing/charging and discharging unit 60, to which the signal V1rectified by the rectifier unit 50 is input, smooths the signal V1. Inaddition, the smoothing/charging and discharging unit 60 charges ordischarges the connecting unit 90 on the basis of the rectified andsmoothed signal V1, and supplies a signal V2 to the connecting unit 90.The signal level of the signal V2 applied to the connecting unit 90changes depending on the signal level of the signal V1.

The connecting unit 90 has transistors controlled by the signal V2 andelectrically connects or disconnects the third terminal 13 and thefourth terminal 14 to or from each other. When the signal Vin becomeshigh level and the signal level of the signal V2 becomes high level, theconnecting unit (switching unit) 90 is switched to the ON state andelectrically connects the third terminal 13 and the fourth terminal 14to each other. When the signal Vin becomes low level and the signallevel of the signal V2 becomes low level, the connecting unit 90 isswitched to the OFF state and electrically disconnects the thirdterminal 13 and the fourth terminal 14 from each other. Thesemiconductor relay device 1 according to the embodiment will be furtherdescribed below with reference to FIG. 2 .

FIG. 2 is a diagram illustrating an example of a circuit configurationof the semiconductor relay device according to the embodiment. As anexample, the inductor unit 40 has an inductor L1 a, an inductor L1 b, aninductor L2 a, and an inductor L2 b as illustrated in FIG. 2 . Theinductors L1 a and L1 b are primary-side inductors and the inductors L2a and L2 b are secondary-side inductors. The primary-side inductors andthe secondary-side inductors are also referred to as primary-sidewindings (primary windings) and secondary-side windings (secondarywindings), respectively. The primary-side inductors and thesecondary-side inductors are electrically isolated from each other andmake energy transmission from the primary side to the secondary side. Itcan also be said that the primary-side inductors and the secondary-sideinductors are electromagnetically connected to each other.

The inductor L1 a is arranged against the inductor L2 a and ismagnetically coupled to the inductor L2 a. The inductor L1 b is arrangedagainst the inductor L2 b and is magnetically coupled to the inductor L2b. One end of each of the inductor L1 a and the inductor L1 b iselectrically connected to the first terminal 11, and the signal Vin isapplied thereto. The other end of each of the inductor L1 a and theinductor L1 b is connected to the driving unit 30.

One end of each of the inductor L2 a and the inductor L2 b is connectedto the rectifier unit 50. The other end of each of the inductor L2 a andthe inductor L2 b is connected to a wiring 102 as illustrated in FIG. 2. The electric potential of the wiring 102 is a reference potential forthe signal V1 and the signal V2 (for example, ground potential).

When current is supplied to a primary-side inductor L1 (L1 a, L1 b),magnetic flux is generated. The magnetic flux generated in theprimary-side inductor L1 is transmitted to a secondary-side inductor L2(L2 a, L2 b), so that electromotive force is induced in thesecondary-side inductor L2. In the inductor unit 40, electromagneticinduction occurs depending on the current input to the primary-sideinductor L1, and electric power can thus be supplied to thesecondary-side inductor L2.

The magnitude of voltage induced in the secondary-side inductor L2 mayvary according to a ratio between the number of turns of theprimary-side inductor L1 to the number of turns of the secondary-sideinductor L2. The number of turns of the primary-side inductor L1 may befewer than the number of turns of the secondary-side inductor L2 so thatthe voltage to be generated in the secondary-side inductor L2 will behigher than the voltage input in the primary-side inductor L1. The ratioof the number of turns may be reversed, that is, the number of turns ofthe primary-side inductor L1 may be more than the number of turns of thesecondary-side inductor L2 so that the voltage to be generated in thesecondary-side inductor L2 will be lower than the voltage input in theprimary-side inductor L1. Alternatively, the same voltage as that in theprimary-side inductor L1 may be generated in the secondary-side inductorL2.

The driving unit 30 has a control unit 31 and a supply unit 35, andcontrols power supply to the inductor unit 40 to control operation ofthe inductor unit 40. In the example illustrated in FIG. 2 , the supplyunit 35 has a transistor 36 a and a transistor 36 b controlled by thecontrol unit 31. The transistor 36 a and the transistor 36 b are MOStransistors (MOSFETs) each having gate, source, and drain terminals.Note that the supply unit 35 may be configured using bipolartransistors.

The gate of each of the transistor 36 a and the transistor 36 b isconnected to the control unit 31. The drain of the transistor 36 a isconnected to an end of the inductor L1 a. The drain of the transistor 36b is connected to an end of the inductor L1 b. The source of each of thetransistor 36 a and the transistor 36 b is electrically connected to thesecond terminal 12 via a wiring 101 as illustrated in FIG. 2 . Areference potential (for example, ground potential) for the signal Vinof the first terminal 11 is applied to the wiring 101 through the secondterminal 12.

The control unit 31 includes, for example, a buffer circuit, an invertercircuit, and the like, and generates, on the basis of the oscillationsignal CLK output from the oscillator unit 20, signals for controllingthe supply unit 35. The control unit 31 supplies the signals forcontrolling the supply unit 35 to the supply unit 35 and controlsoperation of each of the transistors (the transistor 36 a and thetransistor 36 b in FIG. 2 ) of the supply unit 35. The control unit 31supplies the signal to the gate of each of the transistors of the supplyunit 35 to turn the transistor to the ON state (connected state,conductive state, short-circuit state) or to the OFF state (disconnectedstate, non-conductive state, open state, cut-off state).

The control unit 31 performs ON/OFF control of the transistor 36 a andthe transistor 36 b of the supply unit 35 by outputting the signals forcontrolling the supply unit 35 to the supply unit and thereby starts andstops supplying current to the inductor unit 40. The control unit 31 canperform control of supplying current to the inductor L1 a by thetransistor 36 a and control of supplying current to the inductor L1 b bythe transistor 36 b. Note that the driving unit 30 may include theoscillator unit 20.

The rectifier unit 50 is constituted by a rectifier circuit having adiode 51 a and a diode 51 b. The anode (terminal) of the diode 51 a isconnected to the inductor L2 a. The cathode (terminal) of the diode 51 ais connected to the smoothing/charging and discharging unit 60. Inaddition, the anode of the diode 51 b is connected to the inductor L2 b.The cathode of the diode 51 b is connected to the smoothing/charging anddischarging unit 60.

When the transistor 36 a of the supply unit 35 is turned to the ON stateand the transistor 36 b to the OFF state, the inductor L1 a becomeselectrically connected to the second terminal 12. Then, a voltagedepending on the voltage between terminals, that is, between the firstterminal 11 and the second terminal 12 is applied to the inductor L1 a,so that current flows from the first terminal 11 to the inductor L1 a.The current flowing through the inductor L1 a induces magnetic flux,which causes power supply to the inductor L2 a. In this case, the diode51 a of the rectifier unit 50 is turned to the ON state, and currentfrom the inductor L2 a is supplied to the smoothing/charging anddischarging unit 60.

When the transistor 36 a of the supply unit 35 is turned to the OFFstate and the transistor 36 b to the ON state, the inductor L1 b becomeselectrically connected to the second terminal 12. Then, a voltagedepending on the voltage between terminals, that is, between the firstterminal 11 and the second terminal 12 is applied to the inductor L1 b,so that current flows from the first terminal 11 to the inductor L1 b.The current flowing through the inductor L1 b induces magnetic flux,which causes power supply to the inductor L2 b. In this case, the diode51 b of the rectifier unit 50 is turned to the ON state, and currentfrom the inductor L2 b is supplied to the smoothing/charging anddischarging unit 60.

In this way, the inductor unit 40 is controlled by the driving unit 30,and the inductor L1 a and the inductor L1 b are alternately suppliedwith electric power. Therefore, the inductor unit 40 can efficientlytransmit power from the primary-side inductors L1 to the secondary-sideinductors L2. The rectifier unit 50 rectifies AC output generated by theinductor L2 a and the inductor L2 b, and outputs the rectified signal tothe smoothing/charging and discharging unit 60.

The smoothing/charging and discharging unit 60 has a smoothing unit 70and a charging and discharging unit 80. In the example illustrated inFIG. 2 , the smoothing unit 70 is constituted by a capacitor C. Asillustrated in FIG. 2 , an end of the capacitor C is connected to therectifier unit 50 and the charging and discharging unit 80. The otherend of the capacitor C is connected to the wiring 102 that is at thereference potential.

The signal V1 is input to the capacitor C from the inductor L2 a and theinductor L2 b via the rectifier unit 50. The capacitor C accumulateselectric charge depending on the voltage of the signal V1. The capacitorC suppresses fluctuations in the voltage of the signal V1. This makes itpossible to supply steady-level signals to the latter circuit,especially, to the input gates of transistors 91 a and 91 b of theconnecting unit 90.

The charging and discharging unit 80 has a plurality of diodes 81(diodes 81 a to 81 c in FIG. 2 ), a resistance 82, and a transistor 83.The diode 81 a, the diode 81 b, and the diode 81 c are connected inseries. The resistance 82 is connected to the diodes 81 a to 81 c inparallel. The signal V1 is input to the gate of the transistor 83. Thesignal V1 is input from the rectifier unit via the smoothing unit 70 tothe charging and discharging unit 80, which outputs the signal V2 basedon the voltage of the signal V1 to the connecting unit 90.

When the voltage of the signal V1 increases (gets higher), the diodes 81a to 81 c are turned to the ON state, the connecting unit 90 is charged,and the voltage of the signal V2 input to the connecting unit 90increases. When the voltage of the signal V1 decreases (gets lower), thediodes 81 a to 81 c are turned to the OFF state and the transistor 83 isturned to the ON state. In this case, the transistor 83 discharges theconnecting unit 90, resulting in a rapid fall in the voltage of thesignal V2 input to the connecting unit 90.

The connecting unit 90 has a transistor 91 a and a transistor 91 b asillustrated in FIG. 2 . The transistor 91 a and the transistor 91 b areMOS transistors (MOSFETs) each having gate, source, and drain terminals.Note that the connecting unit 90 may be configured using bipolartransistors.

The gate of each of the transistor 91 a and the transistor 91 b isconnected to the charging and discharging unit 80, and the signal V2 isinput thereto. The drain of the transistor 91 a and the drain of thetransistor 91 b are connected to the third terminal 13 and the fourthterminal 14, respectively. The source of each of the transistor 91 a andthe transistor 91 b is connected to the wiring 102.

The transistor 91 a and the transistor 91 b are switched by the signalV2 of which signal level changes depending on the signal Vin. Thetransistor 91 a and the transistor 91 b electrically connect ordisconnect the third terminal 13 and the fourth terminal 14 to or fromeach other depending on the input signal V2.

When the signal V2 becomes low level, the transistor 91 a and thetransistor 91 b are both switched to the OFF state. In this case, thethird terminal 13 and the fourth terminal 14 are electricallydisconnected from each other by the transistor 91 a and the transistor91 b.

When the signal V2 becomes high level, the transistor 91 a and thetransistor 91 b are both switched to the ON state. In this case, thethird terminal 13 and the fourth terminal 14 are electrically connectedto each other by the transistor 91 a and the transistor 91 b.Furthermore, the third terminal 13 and the fourth terminal 14 are bothelectrically connected to the wiring 102, and a potential depending onthe reference potential is applied to the third terminal 13 and thefourth terminal 14. The connecting unit 90 outputs an electrical signalthat serves as the reference potential from the third terminal 13 andthe fourth terminal 14 to outside.

As described above, in the semiconductor relay device 1 according to theembodiment, the driving unit 30 controls power transfer from aprimary-side inductor L1 of the inductor unit 40 to a secondary-sideinductor L2. It is possible to transfer electric power to thesecondary-side inductor L2 in a state where the primary-side inductor L1and the secondary-side inductor L2 are electrically isolated from eachother, and to set the voltage of the secondary-side inductor L2 to avoltage raised or lowered from the voltage of the primary-side inductorL1 or a voltage that is the same as the voltage of the primary-sideinductor L1. It is possible to properly supply the connecting unit 90with the signal V2 with a voltage necessary for switching of theconnecting unit 90 so that switching can be appropriately performeddepending on the signal Vin.

Even in a case where transistors having a large current capacity andthus having a large gate capacitance are used for the connecting unit90, it is possible to supply the signal V2 with large electric powerthat can charge the gate capacitance in a short time. Therefore,switching delays and malfunctions can be prevented.

FIG. 3 is a timing chart illustrating an operation example of thesemiconductor relay device according to the embodiment. The timing chartin FIG. 3 shows, along the same time axis, the signal Vin, theoscillation signal CLK, the gate voltage Vg1 of the transistor 36 a, thedrain voltage Vd1 of the transistor 36 a, the current Id1 flowingthrough the inductor L1 a, the gate voltage Vg2 of the transistor 36 b,the drain voltage Vd2 of the transistor 36 b, the current Id2 flowingthrough the inductor L1 b, and the signal V2.

At the time t1 illustrated in FIG. 3 , the signal Vin becomes highlevel, and output of the oscillation signal CLK starts. In addition, atthe time t1, while the gate voltage Vg1 of the transistor 36 a is at lowlevel, the gate voltage Vg2 of the transistor 36 b becomes high level.When the gate voltage Vg2 of the transistor 36 b becomes high level, thetransistor 36 b is turned to the ON state and current is supplied to theinductor L1 b, so that electric power is accumulated.

At the time t2, the gate voltage Vg1 of the transistor 36 a becomes highlevel, and the gate voltage Vg2 of the transistor 36 b becomes lowlevel. When the gate voltage Vg1 of the transistor 36 a becomes highlevel, the transistor 36 a is turned to the ON state and current issupplied to the inductor L1 a. The current flowing through the inductorL1 a induces magnetic flux, which causes energy supply to thesecondary-side inductor L2, resulting in an increase in the voltage ofthe signal V1 and an increase in the voltage of the signal V2.

After the time t3, as in the period from the time t1 to the time t3,energy supply from the inductor L1 b to the secondary-side inductor L2and energy supply from the inductor L1 a to the secondary-side inductorL2 are alternately performed. In this way, when the signal Vin changesfrom low level to high level, the voltage of the signal V2 increases.This results in switching of the transistors of the connecting unit 90from the OFF state to the ON state, which leads to electrical connectionbetween the third terminal 13 and the fourth terminal 14.

According to the embodiment described above, the following advantageouseffects can be obtained.

(1) A semiconductor relay device 1 includes: an oscillator unit 20configured to output an oscillation signal CLK based on an input signalVin; a first inductor and a second inductor (for example, the inductorL1 a and the inductor L2 a) that are magnetically coupled to each other;a driving unit 30 configured to drive the first inductor based on theoscillation signal CLK output from the oscillator unit 20; a rectifierunit 50 configured to rectify a signal output by the second inductor;and a connecting unit 90 configured to electrically connect ordisconnect a first terminal and a second terminal (the third terminal 13and the fourth terminal 14) to or from each other based on a signalrectified by the rectifier unit 50. In the embodiment, the oscillationsignal CLK from the oscillator unit 20 is input to the driving unit 30,and the driving unit 30 controls power supply to the inductor unit 40.The inductor unit 40 transfers power from the primary-side inductor L1 ato the secondary-side inductor L2 a and from the primary-side inductorL1 b to the secondary-side inductor L2 b in a state where the primaryside and the secondary side are electrically isolated from each other.With this configuration, it is possible to supply the connecting unit 90with the signal V2 with a voltage necessary for switching of theconnecting unit 90. Switching can thus be appropriately performeddepending on the signal Vin.(2) In the embodiment, even in a case where transistors having a largecurrent capacity are used for the connecting unit 90, a large voltagefor driving the transistors can be obtained. Furthermore, switchingdelays and malfunctions can be suppressed.

The following variations also fall within the scope of the presentinvention. It is also possible to combine one or more of the variationswith the above-described embodiment.

(First Variation)

FIG. 4 is a diagram illustrating an example of a configuration of asemiconductor relay device according to a first variation. In theexample illustrated in FIG. 4 , the semiconductor relay device 1 has adetector unit 22. The detector unit 22 detects current supplied to theprimary side of the inductor unit 40 and outputs a signal indicating thedetection result to the oscillator unit 20. Note that the detector unit22 may detect voltage based on the current supplied to the primary sideof the inductor unit 40 and output a signal indicating the detectionresult to the oscillator unit 20.

The oscillator unit 20 acquires the magnitude of current flowing on theprimary side of the inductor unit 40 using the signal detected from thedetector unit 22, and changes the frequency of the oscillation signalCLK. For example, when the current flowing on the primary side of theinductor unit 40 is at or above a predetermined reference level(threshold), the oscillator unit 20 generates an oscillation signal CLKwith a first frequency and outputs it. When the current flowing on theprimary side of the inductor unit 40 drops below the predeterminedreference level, the oscillator unit 20 generates an oscillation signalCLK with a second frequency lower than the first frequency and outputsit. In this case, the value of the second frequency may be adjusted suchthat the connecting unit 90 can stay in the ON state.

FIG. 5 is a diagram illustrating another configuration example of thesemiconductor relay device according to the first variation. In theexample illustrated in FIG. 5 , the detector unit 22 detects currentflowing from the first terminal 11 through some parts of thesemiconductor relay device 1, such as current supplied to the oscillatorunit 20, the driving unit 30, and a primary-side inductor L1 of theinductor unit 40 in FIG. 5 , and outputs a signal indicating thedetection result to the oscillator unit 20. Note that the detector unit22 may detect voltage based on the current supplied from the firstterminal 11 and output a signal indicating the detection result to theoscillator unit 20. Also in the example illustrated in FIG. 5 , theoscillator unit 20 can change the frequency of the oscillation signalCLK depending on the detection result by the detector unit 22.

In this way, the semiconductor relay device 1 according to thisvariation shifts the frequency of the oscillation signal CLK dependingon current flowing through the semiconductor relay device 1. When theconnecting unit 90 changes from the OFF state to the ON state andcurrent flowing through a primary-side inductor drops, the frequency ofthe oscillation signal CLK can be lowered. Therefore, it is possible tomitigate electromagnetic radiation noise caused by the operation of thesemiconductor relay device 1. In addition, it is possible to reducepower consumption of the semiconductor relay device 1.

(Second Variation)

FIG. 6 is a diagram illustrating a configuration example of asemiconductor relay device according to a second variation. In thisvariation, the semiconductor relay device 1 has a timing unit (TIMER)25. The timing unit (measuring unit) 25 starts timing when, for example,the signal Vin changes from low level to high level, and outputs asignal indicating the timing result to the oscillator unit 20.

The oscillator unit 20 changes the frequency of the oscillation signalCLK depending on the signal input from the timing unit 25. When apredetermined time has elapsed after the change of the signal Vin fromlow level to high level, the oscillator unit 20 lowers the frequency ofthe oscillation signal CLK. Note that the timing unit 25 may start timekeeping when the oscillator unit 20 starts outputting the oscillationsignal CLK, and output a signal indicating the timing result to theoscillator unit 20. In this case, the oscillator unit 20 may lower thefrequency of the oscillation signal CLK when a predetermined time haselapsed after the start of the output of the oscillation signal CLK.

The semiconductor relay device 1 according to this variation shifts thefrequency of the oscillation signal CLK depending on the timing resultby the timing unit 25. Therefore, it is possible to mitigate radiationnoise by lowering the frequency of the oscillation signal CLK. Inaddition, it is possible to reduce power consumption of thesemiconductor relay device 1.

(Third Variation)

Although configuration examples of the inductor unit 40 and the drivingunit 30 have been described in the above embodiment and variations, theyare merely examples. For example, the number of inductors of theinductor unit 40 and the arrangement thereof, and the number oftransistors of the driving unit 30 and the arrangement thereof are notlimited to the above examples. As illustrated in FIG. 7 , four inductorsL1 a to L1 d may be arranged as primary-side inductors L1, and fourtransistors 36 a to 36 d may be arranged for controlling the fourinductors, respectively. Furthermore, the control unit 31 may changecontrol of the inductor unit 40 by the supply unit 35 depending on thetiming result by the timing unit 25.

When the signal Vin changes from low level to high level, the controlunit 31 may turn only the transistor 36 a and the transistor 36 d amongthe four transistors to the ON state so as to perform, for a firstperiod, power supply to the inductors L1 a and L1 b by the transistor 36a and power supply to the inductors L1 c and L1 d by the transistor 36d. In this first period, the four primary-side inductors L1 are drivenand thereby sufficient current is supplied to the secondary side. Thus,it is possible to quickly charge the gates of the transistors of theconnecting unit 90 to switch the connecting unit 90 to the ON state. Itis possible to shorten the time from when the signal Vin changes to highlevel until the connecting unit 90 is switched to the ON state.

For a second period following the first period, the control unit 31 mayturn only the transistor 36 b and the transistor 36 c among the fourtransistors to the ON state so as to perform power supply to theinductor L1 b by the transistor 36 b and power supply to the inductor L1c by the transistor 36 c. In this second period, the two primary-sideinductors L1 supply power to the two secondary-side inductors L2 andthereby higher voltage can be generated on the secondary side than inthe first period, so that higher voltage is applied to the gates of thetransistors of the connecting unit 90. This makes it possible to lowerthe on-resistance of the transistors of the connecting unit 90 and tostably maintain the ON state.

Note that, as illustrated in FIG. 8 , two inductors L1 a and L1 d may bearranged as primary-side inductors L1. In this configuration, energy maybe accumulated in the primary-side inductors L1 when the transistors 36are in the ON state, and the energy may be transmitted to thesecondary-side inductor L2 when the transistors 36 are turned to the OFFstate. In the example illustrated in FIG. 8 , the inductor unit 40 canfunction as a flyback transformer.

(Fourth Variation)

FIG. 9 is a diagram illustrating a configuration example of asemiconductor relay device according to a fourth variation. Thesemiconductor relay device 1 includes a sealing portion 110 and a wiringlayer 120. The sealing portion (sealing layer) 110 is in contact withthe wiring layer 120 and is provided to insulate at least a part of eachof a first semiconductor element 201 and a second semiconductor element202. The first semiconductor element 201 is, for example, asemiconductor chip provided with the oscillator unit 20 and the drivingunit 30. The second semiconductor element 202 is, for example, asemiconductor chip provided with the smoothing unit 70 and the chargingand discharging unit 80.

The wiring layer 120 includes a first wiring layer 114 provided with theprimary-side inductor L1 of the inductor unit 40, an isolating layer115, and a second wiring layer 116 provided with the secondary-sideinductor L2 of the inductor unit 40. The first wiring layer 114 and thesecond wiring layer 116 are laminated with the isolating layer 115interposed between the first wiring layer 114 and the second wiringlayer 116.

The primary-side inductor L1 and the secondary-side inductor L2 may bespiral inductors (coils). In the example illustrated in FIG. 9 , theinductor unit 40 functions as a so-called coreless transformer. Theprimary-side inductor L1 and the secondary-side inductor L2 can beformed in a wiring process when the first semiconductor element 201 andthe second semiconductor element 202 are mounted, allowingminiaturization of the semiconductor relay device 1. The inductor unit40 also functions with a configuration using a magnetic body.

The various embodiments and variations have been described above, butthe present invention is not limited to the details thereof. Anothermode conceivable within the technical idea of the present invention alsofalls within the scope of the present invention.

REFERENCE SIGNS LIST

-   -   1: semiconductor relay device    -   11: first terminal    -   12: second terminal    -   13: third terminal    -   14: fourth terminal    -   20: oscillator unit    -   30: driving unit    -   31: control unit    -   35: supply unit    -   40: inductor unit    -   50: rectifier unit    -   60: smoothing/charging and discharging unit    -   70: smoothing unit    -   80: charging and discharging unit    -   90: connecting unit

1. A semiconductor relay device comprising: an oscillator unitconfigured to output an oscillation signal based on an input signal; afirst inductor and a second inductor that are magnetically coupled toeach other; a driving unit configured to drive the first inductor basedon the oscillation signal output from the oscillator unit; a rectifierunit configured to rectify a signal output by the second inductor; and aconnecting unit configured to electrically connect or disconnect twoterminals to or from each other based on a signal rectified by therectifier unit, wherein an electrical signal is output from the twoterminals to outside, wherein the semiconductor relay device furthercomprises a wiring layer in which a first wiring layer including thefirst inductor and a second wiring layer including the second inductorare laminated with an isolating layer interposed between the firstwiring layer and the second wiring layer, and wherein a semiconductorelement having the oscillator unit and the driving unit is arranged onthe wiring layer.
 2. The semiconductor relay device according to claim1, wherein the driving unit is configured to transfer, based on theoscillation signal output from the oscillator unit, electric powersupplied to the first inductor to the second inductor in an isolatedmanner at a raised or lowered voltage, or at a same voltage.
 3. Thesemiconductor relay device according to claim 1, wherein the drivingunit has a supply unit configured to supply current to the firstinductor, and a control unit configured to control supply of the currentby the supply unit based on the oscillation signal.
 4. The semiconductorrelay device according to claim 3, comprising a plurality of the firstinductors, wherein the supply unit has a first transistor connected to asubset of the first inductors among the plurality of the firstinductors, and a second transistor connected to another subset of thefirst inductors among the plurality of the first inductors.
 5. Thesemiconductor relay device according to claim 4, wherein the controlunit is configured to perform control of supplying current to the firstinductor by the first transistor and control of supplying current to thesecond inductor by the second transistor.
 6. The semiconductor relaydevice according to claim 1, comprising a timing unit, wherein theoscillator unit is configured to change a frequency of the oscillationsignal based on a timing result by the timing unit.
 7. The semiconductorrelay device according to claim 1, comprising a detector unit configuredto detect current supplied to the first inductor or voltage based on thecurrent supplied to the first inductor, wherein the oscillator unit isconfigured to change a frequency of the oscillation signal based on adetection result by the detector unit.
 8. The semiconductor relay deviceaccording to claim 1, comprising a smoothing unit configured to smooththe signal rectified by the rectifier unit.
 9. The semiconductor relaydevice according to claim 8, wherein the connecting unit has a thirdtransistor for electrically connecting the two terminals to each other,and the semiconductor relay device comprises a charging and dischargingunit configured to charge or discharge a gate of the third transistorbased on the signal rectified by the rectifier unit.
 10. (canceled) 11.The semiconductor relay device according to claim 9, wherein thesmoothing unit and the charging and discharging unit are arranged on thewiring layer.